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Johansson, Lars
Publications (10 of 13) Show all publications
Lindström, S. B., Johansson, L. & Karlsson, N. R. (2014). Metastable states and activated dynamics in thin-film adhesion to patterned surfaces. Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 89, 062401-1-062401-11
Open this publication in new window or tab >>Metastable states and activated dynamics in thin-film adhesion to patterned surfaces
2014 (English)In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 89, p. 062401-1-062401-11Article in journal (Refereed) Published
Abstract [en]

We consider adhesion due to London–van der Waals attraction between a thin film and a patterned surface with nanometer asperities. Depending on the surface topography and the stiffness of the film, three regimes of adhesion are identified: complete contact adhesion, partial contact adhesion, and glassy adhesion. For complete contact adhesion, the film conforms to the undulations of the surface, whereas for partial contact and glassy adhesion, the adhesive interface breaks down into microscopic areas of contact. When a film in the glassy regime is peeled off the surface, metastable states develop at which the crack front becomes arrested, analogously to the frustrated motion of the three-phase contact line across a heterogeneous surface. For this glassy regime, we use transition state theory to model the thermally activated progression of the crack front. This theoretical treatment suggests that the rate of the adhesive failure increases exponentially with the applied force.

Place, publisher, year, edition, pages
American Physical Society, 2014
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-110756 (URN)10.1103/PhysRevE.89.062401 (DOI)000346849600002 ()
Available from: 2014-09-21 Created: 2014-09-21 Last updated: 2017-12-05Bibliographically approved
Fahlgren, A., Johansson, L., Edlund, U. & Aspenberg, P. (2012). Direct ex vivo measurement of the fluid permeability of loose scar tissue. Acta of Bioengineering and Biomechanics, 14(2), 47-51
Open this publication in new window or tab >>Direct ex vivo measurement of the fluid permeability of loose scar tissue
2012 (English)In: Acta of Bioengineering and Biomechanics, ISSN 1509-409X, Vol. 14, no 2, p. 47-51Article in journal (Refereed) Published
Abstract [en]

Fluid flow is important in many biomechanical models, but there is a lack of experimental data that quantifies soft tissue permeability. We measured the tissue permeability in fibrous soft tissue, using a novel technique to obtain specimens by allowing soft tissue to grow into coralline hydroxyapatite scaffoldings implanted between the abdominal muscle layers of rats.

Place, publisher, year, edition, pages
Wroclaw, Poland: Wroclaw University of Technology, 2012
Keywords
permeability, Darcys law, soft tissue, hydraulic conductivity
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-93986 (URN)10.5277/abb120206 (DOI)000318777500006 ()
Available from: 2013-06-13 Created: 2013-06-13 Last updated: 2014-02-27Bibliographically approved
Johansson, L., Edlund, U., Fahlgren, A. & Aspenberg, P. (2011). Fluid-induced osteolysis: modelling and experiments. COMPUTER METHODS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING, 14(4), 305-318
Open this publication in new window or tab >>Fluid-induced osteolysis: modelling and experiments
2011 (English)In: COMPUTER METHODS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING, ISSN 1025-5842, Vol. 14, no 4, p. 305-318Article in journal (Refereed) Published
Abstract [en]

A model to calculate bone resorption driven by fluid flow at the bone-soft tissue interface is developed and used as a basis for computer calculations, which are compared to experiments where bone is subjected to fluid flow in a rat model. Previous models for bone remodelling calculations have been based on the state of stress, strain or energy density of the bone tissue as the stimulus for remodelling. We believe that there is experimental support for an additional pathway where an increase in the amount of the cells directly involved in bone removal, the osteoclasts, is caused by fluid pressure, flow velocity or other parameters related to fluid flow at the bone-soft tissue interface, resulting in bone resorption.

Place, publisher, year, edition, pages
Taylor and Francis, 2011
Keywords
bone resorption, theory of mixtures, experimental model, finite element method
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-67561 (URN)10.1080/10255842.2010.484808 (DOI)000288951800001 ()
Available from: 2011-04-18 Created: 2011-04-18 Last updated: 2012-03-22
Fahlgren, A., Bostrom, M. P., Yang, X., Johansson, L., Edlund, U., Agholme, F. & Aspenberg, P. (2010). Fluid pressure and flow as a cause of bone resorption. Acta Orthopaedica, 81(4), 508-516
Open this publication in new window or tab >>Fluid pressure and flow as a cause of bone resorption
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2010 (English)In: Acta Orthopaedica, ISSN 1745-3674, E-ISSN 1745-3682, Vol. 81, no 4, p. 508-516Article in journal (Refereed) Published
Abstract [en]

Background Unstable implants in bone become surrounded by an osteolytic zone. This is seen around loose screws, for example, but may also contribute to prosthetic loosening. Previous animal studies have shown that such zones can be induced by fluctuations in fluid pressure or flow, caused by implant instability. Method To understand the roles of pressure and flow, we describe the 3-dimensional distribution of osteolytic lesions in response to fluid pressure and flow in a previously reported rat model of aseptic loosening. 50 rats had a piston inserted in the proximal tibia, designed to produce 20 local spikes in fluid pressure of a clinically relevant magnitude (700 mmHg) twice a day. The spikes lasted for about 0.3 seconds. After 2 weeks, the pressure was measured in vivo, and the osteolytic lesions induced were studied using micro-CT scans. Results Most bone resorption occurred at pre-existing cavities within the bone in the periphery around the pressurized region, and not under the piston. This region is likely to have a higher fluid flow and less pressure than the area just beneath the piston. The velocity of fluid flow was estimated to be very high (roughly 20 mm/s). Interpretation The localization of the resorptive lesions suggests that high-velocity fluid flow is important for bone resorption induced by instability.

Place, publisher, year, edition, pages
Taylor & Francis, 2010
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-58811 (URN)10.3109/17453674.2010.504610 (DOI)000282742300016 ()
Available from: 2010-09-02 Created: 2010-08-27 Last updated: 2017-12-12
Johansson, L., Edlund, U., Fahlgren, A. & Aspenberg, P. (2009). Bone Resorption Induced by Fluid Flow. Journal of Biomechanical Engineering, 131(9), 094505-1-094505-5
Open this publication in new window or tab >>Bone Resorption Induced by Fluid Flow
2009 (English)In: Journal of Biomechanical Engineering, ISSN 0148-0731, E-ISSN 1528-8951, Vol. 131, no 9, p. 094505-1-094505-5Article in journal (Refereed) Published
Abstract [en]

A model where bone resorption is driven by stimulus from fluid flow is developed and used as a basis for computer simulations, which are compared with experiments. Models for bone remodeling are usually based on the state of stress, strain, or energy density of the bone tissue as the stimulus for remodeling. We believe that there is experimental support for an additional pathway, where an increase in the amount of osteoclasts, and thus osteolysis, is caused by the time history of fluid flow velocity, fluid pressure, or other parameters related to fluid flow at the bone/soft tissue interface of the porosities in the bone.

Place, publisher, year, edition, pages
ASME, 2009
Keywords
bone resorption, constitutive model
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:liu:diva-20801 (URN)10.1115/1.3194756 (DOI)
Available from: 2009-09-21 Created: 2009-09-21 Last updated: 2017-12-13
Johansson, L., Edlund, U., Fahlgren, A. & Aspenberg, P. (2006). A model for bone resorption. In: ESDA 2006, 8th Biennial ASME Conference on Engineering Systems Design and Analysis,2006: . Paper presented at 8th Biennial ASME Conference on Engineering Systems Design and Analysis (pp. 487-495). ASME Press
Open this publication in new window or tab >>A model for bone resorption
2006 (English)In: ESDA 2006, 8th Biennial ASME Conference on Engineering Systems Design and Analysis,2006, ASME Press, 2006, p. 487-495Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
ASME Press, 2006
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-41380 (URN)10.1115/ESDA2006-95401 (DOI)55878 (Local ID)0-7918-3779-3 (ISBN)55878 (Archive number)55878 (OAI)
Conference
8th Biennial ASME Conference on Engineering Systems Design and Analysis
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2014-11-17
Johansson, L. (2004). Privatlärare drev fram mattesnillen. Svenska dagbladet (2 november), 63-63
Open this publication in new window or tab >>Privatlärare drev fram mattesnillen
2004 (Swedish)In: Svenska dagbladet, ISSN 1101-2412, no 2 november, p. 63-63Article in journal (Other (popular science, discussion, etc.)) Published
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-22573 (URN)1846 (Local ID)1846 (Archive number)1846 (OAI)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2011-01-12
Ciavarella, M., Johansson, L., Afferrante, L., Klarbring, A. & Barber, J. (2003). Interaction of thermal contact resistance and frictional heating in thermoelastic instability. International Journal of Solids and Structures, 40(21), 5583-5597
Open this publication in new window or tab >>Interaction of thermal contact resistance and frictional heating in thermoelastic instability
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2003 (English)In: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 40, no 21, p. 5583-5597Article in journal (Refereed) Published
Abstract [en]

Thermoelastic contact problems can posess non-unique and/or unstable steady-state solutions if there is frictional heating or if there is a pressure-dependent thermal contact resistance at the interface. These two effects have been extensively studied in isolation, but their possible interaction has never been investigated. In this paper, we consider an idealized problem in which a thermoelastic rod slides against a rigid plane with both frictional heating and a contact resistance. For sufficiently low sliding speeds, the results are qualitatively similar to those with no sliding. In particular, there is always an odd number of steady-state solutions, if the steady-state is unique it is stable and if it is non-unique, stable and unstable solutions alternate, with the outlying solutions being stable. However, we identify a sliding speed V0 above which the number of steady states is always even (including zero, implying possible non-existence of a steady-state) and again stable and unstable states alternate. A parallel numerical study shows that for V > V0 there are some initial conditions from which the contact pressure grows without limit in time, whereas for V < V0 the system will always tend to one of the stable steady states. © 2003 Elsevier Ltd. All rights reserved.

Keywords
Thermal contact resistance, Thermoelastic contact, Thermoelastic instability (TEI), Uniqueness
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-46475 (URN)10.1016/S0020-7683(03)00313-5 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
Johansson, L. (2001). A flight dynamics course based on MTLAB computer assignme.
Open this publication in new window or tab >>A flight dynamics course based on MTLAB computer assignme
2001 (English)Other (Other (popular science, discussion, etc.))
Abstract [en]

    

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-35390 (URN)26545 (Local ID)26545 (Archive number)26545 (OAI)
Available from: 2009-10-10 Created: 2009-10-10
Johansson, L. (2001). A Newton method for rigid body frictional impact with multiple simultaneous impact points. Computer Methods in Applied Mechanics and Engineering, 191(3-5), 239-254
Open this publication in new window or tab >>A Newton method for rigid body frictional impact with multiple simultaneous impact points
2001 (English)In: Computer Methods in Applied Mechanics and Engineering, ISSN 0045-7825, E-ISSN 1879-2138, Vol. 191, no 3-5, p. 239-254Article in journal (Refereed) Published
Abstract [en]

In this paper a mathematical formulation and a numerical algorithm for the analysis of frictional impact of rigid bodies with multiple simultaneous contact points are developed. A direct approach is used where the impenetrability condition and Coulomb's law of friction are formulated as equations, which are not differentiable in the usual sense, and solved together with the equations of motion and necessary kinematical relations using Newton's method. An experiment has also been performed where a possible mechanism for the difference between static and dynamic friction is observed and results are compared with computations using the present algorithm. (C) 2001 Elsevier Science B.V. All rights reserved.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-49057 (URN)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-12
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